1. Field of the Invention
The present invention relates to a rotary electric machine such as an automotive alternator, and particularly relates to a permanent magnet holding construction in a Lundell rotor.
2. Description of the Related Art
Automotive alternators that use Lundell rotors have been used in automobiles for decades. Loads from electrical equipment that is mounted due to environmental issues have been increasing rapidly in recent years, and further increases in generated power are being sought from Lundell rotors.
In view of these conditions, generated power has conventionally been increased by disposing permanent magnets on yoke portions of a Lundell rotor so as to face claw-shaped magnetic pole portions to alleviate magnetic saturation of the pole core (See Patent Literature 1, for example).    Patent Literature 1: Japanese Patent Laid-Open No. 2010-187476 (Gazette)
In conventional automotive alternators such as that described in Patent Literature 1, in order to increase resistance of the permanent magnet holding construction to centrifugal forces, permanent magnets are held in magnet holders by being fitted into magnet interfitting grooves that have trapezoidal cross sections that are formed on upper surfaces of the magnet holders. For this reason, because the cross-sectional shape of the permanent magnets is a trapezoidal shape, for example, and the volume of the permanent magnets cannot be increased, and increases in the amount of power generated due to disposing the permanent magnets are reduced.
In conventional automotive alternators such as that described in Patent Literature 1, because no consideration has been given to preventing rotation of a bobbin onto which a field coil is wound that is mounted to a boss portion between yoke portions, one disadvantage has also been that when the rotor is rotated at high speed and a high angular speed is applied to the bobbin, the bobbin may rotate around the axis of the boss portion, causing breakages in output wires of the field coil.